CVE-2025-48812 is a medium severity vulnerability classified as CWE-125 (Out-of-bounds Read) affecting Microsoft Excel in Microsoft 365 Apps for Enterprise version 16.0.1. The flaw allows an attacker to craft a malicious Excel file that, when opened by a user, triggers Excel to read memory outside the allocated buffer boundaries. This out-of-bounds read can lead to unauthorized disclosure of sensitive information residing in adjacent memory areas. The vulnerability does not require any privileges or prior authentication but does require user interaction to open the malicious file. The attack vector is local, meaning the attacker must deliver the malicious file to the victim and convince them to open it. The vulnerability impacts confidentiality but does not compromise integrity or availability of the system. Currently, there are no known exploits in the wild, and no official patches have been released yet. The CVSS 3.1 score of 5.5 reflects the moderate risk posed by this vulnerability, balancing the ease of exploitation with the limited scope of impact. Organizations using Microsoft 365 Apps for Enterprise should monitor for updates and prepare to deploy patches promptly once available.

For European organizations, this vulnerability poses a risk of local information disclosure, potentially exposing sensitive data stored in memory to unauthorized parties. This could include credentials, personal data, or proprietary information, depending on what resides in the memory regions read out-of-bounds. While the attack requires user interaction, phishing or social engineering campaigns could be used to deliver malicious Excel files. The impact is particularly relevant for sectors handling sensitive or regulated data such as finance, healthcare, and government. Although the vulnerability does not allow remote code execution or system compromise, the leakage of confidential information could lead to further targeted attacks or compliance violations under regulations like GDPR. The absence of known exploits reduces immediate risk, but the widespread use of Microsoft 365 in Europe means many endpoints could be vulnerable if patches are delayed.

1. Apply security updates from Microsoft promptly once patches for CVE-2025-48812 are released. 2. Until patches are available, restrict the opening of Excel files from untrusted or unknown sources, especially via email or external downloads. 3. Employ advanced endpoint protection solutions that include memory protection and anomaly detection to identify suspicious Excel behaviors. 4. Educate users on the risks of opening unsolicited or unexpected Excel attachments and encourage verification of file sources. 5. Use application control policies to limit execution of untrusted macros or embedded content within Excel files. 6. Monitor network and endpoint logs for unusual activity related to Excel processes. 7. Consider deploying Microsoft Defender Exploit Guard or similar tools to enforce exploit mitigation policies. 8. Maintain regular backups and incident response plans to quickly address any potential data exposure incidents.